To take the wind out of someone's sails

Origin

The phrase hails from the golden age of sailing, where naval battles and races relied heavily on skillful navigation and understanding of wind dynamics. A cunning captain could maneuver their ship directly in front of an opponent's vessel, effectively blocking the wind from reaching the rival's sails. This strategic move would cause the trailing ship to lose its momentum, slow down, or even stop dead in the water, giving the first ship a decisive advantage. This powerful visual of an opponent suddenly becalmed and rendered helpless by a strategic maneuver has since become a potent metaphor for thwarting someone's plans or deflating their spirits.